xfs: prevent kernel crash due to corrupted inode log format

Andras Korn reported an oops on log replay causes by a corrupted
xfs_inode_log_format_t passing a 0 size to kmem_zalloc.  This patch handles
to small or too large numbers of log regions gracefully by rejecting the
log replay with a useful error message.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: Andras Korn <korn-sgi.com@chardonnay.math.bme.hu>
Reviewed-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: Felix Blyakher <felixb@sgi.com>

1 files changed, 13 insertions, 4 deletions

diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index b1047de2fffd..61af610d79b3 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -1455,10 +1455,19 @@ xlog_recover_add_to_trans(
         item = item->ri_prev;
 
         if (item->ri_total == 0) {              /* first region to be added */
-                item->ri_total  = in_f->ilf_size;
-                ASSERT(item->ri_total <= XLOG_MAX_REGIONS_IN_ITEM);
-                item->ri_buf = kmem_zalloc((item->ri_total *
-                                            sizeof(xfs_log_iovec_t)), KM_SLEEP);
+                if (in_f->ilf_size == 0 ||
+                    in_f->ilf_size > XLOG_MAX_REGIONS_IN_ITEM) {
+                        xlog_warn(
+        "XFS: bad number of regions (%d) in inode log format",
+                                  in_f->ilf_size);
+                        ASSERT(0);
+                        return XFS_ERROR(EIO);
+                }
+
+                item->ri_total = in_f->ilf_size;
+                item->ri_buf =
+                        kmem_zalloc(item->ri_total * sizeof(xfs_log_iovec_t),
+                                    KM_SLEEP);
         }
         ASSERT(item->ri_total > item->ri_cnt);
         /* Description region is ri_buf[0] */